The present disclosure relates to an optical scanning device, an image forming apparatus with an optical scanning device, and a method for adjusting the mass of an oscillating mirror part of an optical scanning device.
Resonant optical scanning devices are known which include an oscillating mirror part and a torsion bar part supporting the oscillating mirror part. In optical scanning devices of this type, the mass of the oscillating mirror part is often adjusted in order to adjust the resonant frequency. For example, there is known an optical scanning device (a general device A) in which the mass of the oscillating mirror part is adjusted by removing a portion of the back surface of the oscillating mirror part (an opposite surface to a reflective surface thereof) by laser processing.
Furthermore, resonant optical scanning devices include those in which the oscillating mirror part is accommodated in a closed housing in order to prevent contamination of the oscillating mirror part. In relation to this, there is known an optical scanning device (a general device B) in which the mass of the oscillating mirror part is adjusted with the oscillating mirror part accommodated in the housing. This optical scanning device includes a mass adjustment part formed on a surface of the oscillating mirror part and capable of changing the mass by a chemical reaction with a gas and is configured to adjust the mass of the oscillating mirror part by adjusting the amount of the chemical reaction.